The effects of the chemical hepatocarcinogen N-2-acetylaminofluorene on rat liver cells in vitro and in vivo will be determined. On-going studies have resulted in characterization of an adult hepatocyte culture system that reproduces the properties of adult regenerating liver cells in vitro. These hepatocyte cultures are able to metabolize the procarcinogen to its active form in vitro. The effect of hepatocarcinogen exposure on these cultures will now be determined. Some parameters that will be measured include alphafetoprotein and albumin production, proliferation, morphologic effects and in vivo growth upon transfer of cells exposed to carcinogen in vitro to syngeneic recipient rats. In addition, adult rats will be fed carcinogenic doses of N-2-FAA for different periods of time and the in vitro growth and protein production of newly appearing cell populations as well as remaining hepatocytes determined by removing the cells from donor carcinogen animals and culturing them in vitro. These studies should help clarify some of the early effects of chemical hepatocarcinogens.